Telephony.



M. L. JOHNSON.

TELEPHONY.

APPLICATION FILED AUG. 10, 191]..

Patented July 2s, 1914.

SHEET l.

s SHEETS- S @RENNEN Ensim@ SES MNLWS NUL .NN MM H MMI@ ww MN- QN p Il m U h H ini Nm Q NN mm. m23 r Hm .N .HONLN /NVENOH HORTON; L JOHNSON.

M. L. JOHNSON.

TELEPHONY.

APPLICATION FILED AUG. 10, 1911.

Patented July 28, 1914.

3 SHEETS-SHEET 2.

TTORNE Y v NORTON. L. JoHNSoN M. L. JOHNSON.

TELEPHONY.

APPLICATION FILED AUG. 1o, 1911.

Patented July 28, 1914.

BSHBETS-SHBBT 3.

/NVENTH MORZ'OML JOHNSON ATTORNE Y vsecond exchange.

.narran sTaTiis raTjnnT onrion NORTON L. JOHNSON, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 FRANK B. COOK COMPANY, 0F CHICAGO, ILLLINOIS, A CORPORATION OF ILLNOIS.

messia.

Speciieation of Letters Patent Application tiled August 10. 1911.

Patented JiulfiY 28, 1914.

Serial No. 643,34).

' ie it known that l. itlou'roN i). Jonxsox.J citizen ot the llnited States, residing at thicag'o. in the county of Cook and State ot illinois. have invented a certain new and useful improvement in Telephony, of which the tollowiucy is' av full, clear. concise. and exact description. re'lercnce beinghad to the accompanyiiigl drawings, forming a part et this specification.

My invention relates to telephone exchange systems and has a number of objects and advantages in view.

One feature of my invention, as preferably einlnulied.y comprises a telephone tcm which includes acoinmon battery exchange to which telephone lines extend. a

second common battery exchange to which other telephone lines extend, atrunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending' to one exchange and a telephone line extending to the secondv exchange. there being' link connectors at the second exchange tor connecting lines extending' to the second exchange and for connecting' lines extendimi` to the second exchange with the. trunk line in the establishment ot a connection between lines extending` to the two exchanges. and means t'or removing` the common battery ot the secondexchange' fromit-s normal relation with the link connector united with the trunk line at the second exchange to bring` the common battery ot the tirst, exchange into operative association with said link connector at the second exchange.

Another feature of my invention resides in providing' means 'for removing' normal bridge connections at 1die second exchange from the' composite telephone circuit between stations of connected lines that extend to the exchanges. Then the exchanges are common battery exchanges the removal of the normal bridge connections enables the common battery at the tirst exchange to perform the tunctions that. would otherwise be required ofthe common battery at the l. do net wish to be limited, however, to the employment ocommon batter i exchanges in ractisinv'fin invention.

In accordance with another feature of my invention the trunk line that intervenes between the exchanges is provided with a switching' mechanism for permitting` it to be divided in sci iarate sections, there being a magnet for governing' said switching' mechamsm located upon that side ot' the trunk line that lis in more immediate association with the telephone line of the second exchange and which magnet is within the control ot' the substation apparatusl 0f a line extending to the second exchange to disjoint the. trunk line.

T here are other features of my invention which will be more lfully hereinafter setl forth. y

I will explain my invention more fully by reference to the accompanying` drawings in which- Figure -1 illustrates a portion of an automatic telephone exchange system and a line extending; thereto from an automatic subscribers station; Fig. 2 illustrates, at its left hand end, a eomplemental portion of the automatic exchange illustrated in Fig. l and also shows a trunk line extending from the automatic exchange to a spring` jack at the i ranch exchange togetl'ier with a plug` of-a private branch exchange cord circuit inserted therein: Fig. Si illustrates a link connector at the branch exchange and a local line extending` trom a telephone station to the i branch exchange. Figs. l. Q and 3 being readable inconnection with each other by placing the tops and bottoms of the sheets containingl Figs l and together' and the tops and bottoms ot the sheets containing Figs. 2 and 3 together; l illustrates a portion ot a manual exchange and a. manual subscribers line extending' thereto; Fig. 5 illustrates at its lett hand end a complemental portion of the manual exchange illustrated in Fig. Ll and also illustrates a trunk line extending` from the manual exchange to the private branch exchange; and Fig. 6 illustrates a link connector at the private branch exchange and al private branch line extending` from a telephone station to the private branch exchange, Figs. 4e, 5 and .G being readable in connection with eachother by an assembly thereof similar to that above described in'connection with Figs. 1, 2 and-.3.

trated'in Figs. t, 5 and G, this being the simpler equipment. As illustrated in Fig. 4C, each telephone line that extends from a Cri substation to a manual exchange is provided with two limbs 1, 2 intervening between the substation and the exchange and there `ter ininating in tip and sleeve line springs 3 and -l oi: a spring jack 5. A switch ,hook 6 is provided at each substation, the normal contact of this switch hook serving to iniyludc a condenser 7 and a signal bell S in bridge o't the line sides 1 and 2 when the telephone receiver 9 is upon its switch hook, the alternate contact of said switch hook serving to include the telephone receiver 9 and *the telephone trai'isniit-ter 10 in bridge of the telephone lines when the switch hook is relieved of the weight of the receiver. Each line is shown as being equipped with a cutotl' relay 11, whose armatures when in normal positions serve to include a line re-A lay 1Q in serial relation with the sides 1, 2 of the associate line and a battery 13, eircuit through the relay 12 being closed when the receiver 9 at the associate telephone station is removed from its switch hook, in a manner well known. A local circuit is closed through a line signal device 14 by the relay 12 when this relay is energized in a manner well known. The circuit of the relay 19J includes the armature switches of the cutott relay 11, this cutoff relay being energized when a plug of a link circuit is inserted in the corresponding jack to open the circuit ofthe relay 12 to causetl'ie ar-' mature of this relay to fall back and open the circuit of the line signal device 14. all as is well understood by those skilled in the art. i i is in the form of a plug ended cord circuit oii a well known type, this cord circuit including` an answering plug 15 and aconnecting plug 1G, the tip sectionsot these plugs being united by a tip strand and the sleeve portions by a sleeve strand. Each strand of the link circuit is rendered metallically discontinuous by a condenser 17 which preserves the continuity of its strand with relation to telephonie current. The answering end of the link circuit includes a relay 1S in bridge thereof while the connecting end ot the link circuit includes a relay 19 in bridge thereof, a battery, which may be the saine battery 13, being common to the bridge conductors containing the relays 1S and 19 as illustrated. lVhen a connection has been established, circuit'through the calling subscribers relay 1S is completed through the calling subscribers switch hook and the alternate contact of such switch hook, while circuit 4is closed through the called subscribers relay 19 through the switch hook at the called station and its alternate contact. The answering end of theV link circuit is provided with a supervisory signal Q0, in accordance with well known practice, that is included inA a local circuit that includes .the common battery, a

The link circuit shown in Fig. el"

answering plug' from its jack. The connecting end of the link circuit is providedV with a lamp 21 whose circuit is siinilarlygoverned by the connecting plug, the jack engaging the same, the telephone apparatus at the private branch station illustrated at the right of Fig. 6 through the intermediation of connections with the connecting plug 16 in Fig. 4, certain connections ,shown in Fig. 5 and certain connections shown in `Fig. 6 as will later appear. In Fig. 1 I

have illustrated an operatoi"slisteni ng' key 22 and an operators ringing key 'Q3-"but have omitted the operators telephone `set and the generator as the association of these elements is well understood.

'The main exchange illustrated in Fig. 1L'

enable the manual line to become connected with a private branch line, one vsuch trunk. line connection being illustrated at the left.

of 5 where there is shown the main exiv change termination of a-two way trunlr line` whose sides 2d, 25 terminate in tiptand sleeve" y fico catediat the main exchange. the other ends` `is provided with trunk line connections -to n of these trunk line sides terminating respeci tively in a tip linespring "29 and a-sleeve' line spring 30 of ati'i'i'iilejack 431 located at the private branch exchange. sides Q4, 25 include, respectively, the nor- Ymally-'separated contacts et' the armature switches 32, the contacts of these armature switches being closed when the relay 34; controlling the sameis energized in the mauner to be described. f A" suitable sortv of signal 35, a drop being illustrated, is in bridge of the trunk'sides at the branch exchange,

the operator at the main exchange operating the signal device `35'by operating` thering; ing'key 23.' The operator-'at the private branch exchange responds to the signal conveyed at 35 by inserting withinV the trunk jack 31 eitlierthe answering plug 3G or the connecting plug 37 of a cord circuit that may .be used for joining two private'branch lines The tru nk."

iis

.aconsequence of the insertionof theplug 3G in the jackl 3l. Then the niag'i-iet-Sis ener-'- gized its armature',moves-a starwheelrlll one step (the armature ofinagnetBSfwhen released assuming a position to enable it to more the wheel 401 another step upon an" other euergisation of the magnet 38) to turn- 43, the contacts 42 when engaged, to ground.

The lowerinost armature switch of the relay -43 vestablishes a circuit -for the sluggishly acting relay 34 at the trunk side gaps 32, 33, the circuit then establisheclior the relay 31 .being traceable from a grounded battery which may be-the battery 39, through the winding` of the relay 34, thence to ground through the lowerin'ost armature switch or rela-y The relay 43 also establishes a circuit, by way of its upper armature switch,

that may be traced from a grounded battery, which may be the battery 39, through the sluggishly acting relay 44, -contacts ofthe upper armature switch of relay 43 to ground. The armature switch of relay 44, "when Operated, serres to close-a gap in la bridge be'A tween trunk sides, which bridgeincludes a relay 45. elay 45 is thereupon'energized owing to the fact that the battery 13 at the main exchange is now in bridge of the trunk sides 24 and 25 and is in circuit with the' winding of relay owing to the closureof the gaps 33 in the trunk sides24, 25.

-lVhen circuit is broken at 42, .thecircuit-"prer riously trac-ed for the relay is broken .at the low l' armature switch of relay 43,' but a circuit closureinsubstitution-forfthat previously occasioned at fthe lower armature switch of relay 48occursat the armature switch of relay 46, the circuit then establ lished for therelay 34 being traceable fromthe grounded battery 39 through the winding oit' the relay 34, the armatureswitch of relay' 4.6` and the closedA contacts 40,A toy f ground, the armature switch of vrelay 46 being ,closed when the relay 45 is included in circuit since the relay 46is in serial relation, with the relay 45. T he relay 34, be1ng-`slug-:;.

gisli, aiiiords ample opportunity for energization of the relays 44, 4.5 and '46 before the circuit 'for the relay'34fis broken at the lower armature switclrloi'iv relay 43. The relay 43 beingsluggish affords ample opportunity for the energization of relays 4 4, 45 and 45 tacts 42.

during the momentary closure of the conv- Therelay 44, having been energized,-dueindircctly to the momentary clusu fe oficircuitat 42, is to be included in another circuit foi-'the purpose of maintaining the-circuit-for the relays45 and To this end the lower armature switch of relay 43 establishes a closed local circuit through the relay44 which is so apparent as not to require tracing. The relay 44' is made sluggish so'that it will notrespoiid when flashing occurs at 'either of two stations connected by way of the trunk line, circuit for the relay 44 opening at the lower armature switch of relay 45 as a consequence of such flashing owing to the fact that the relay 45, as well as the relay 46, are not sluggishly'acting.

' rl`he' upper. armature switch of relay 45 serves to establish circuit through a signal device 47 by a circuit which is so clearly illustrated :1s not to require description,'the device 47 displaying a signal until the called party answers or until the connection taken down.' The bridgedi'elay 45 has its circuit opened, in a manner to be described,- when the-called party responds, the serially related relay 4&5, however, remaining energized during the time the called subscriber' has his telephone in use so that the circuit for the magnet 34 is not disturbed.' T he relay 46 is denergized when the called party restores his telephone upon its switch hook -or when the plug is removed from the cor- 48, to a Vgrounded battery, which may-be the battery 39.' The relay 4S 4thereuponopf' crates its 'armature switches for the purpose of` removing the grounded battery 39 and the ground49 from connection with the talking sidesl of the link circuit shown4 in Lig. so vthat-these talking sides' "may bein'- .circuit relation with the 'battery i3` at the' 'inain exchange exclusively whereby. the link circuit shown in Fig. G, which is ordinarily adapted to the connection of private branch lines owing to the noi-mal presenceof the battery 39 and ground 49, in'ay'be adapted to trunk line connection.l Armature switches controlled by the relay^48 are introduced into circuit with vthe ground'49and battery B'fto. break 'the connections, under the circumstances described, of these elei'nents with theystrandsv ofthe link circuit, which connections were hitherto. permanent.

. The .operations which have been. de-

r'sc ribeihexcepting those which occur at the yc :alled station, having been pei-formed, the' ',Oper'ator manipulates her listening key 50 `to'include her telephone set 5l in bridge of the strands of the cord circuit having plugs 36, 37 shown in Fig. G. Assuming that the iocsubsciiberls station illustrated Aat the left hand of Fig. desires connection with the subscribers station shown at the right hand end of Fig. (3, the opera-tor willinsert that plug of the two plugs 86, 3T which has not been inserted in the jack 31', int-o the a'ck 5 of thev private branch line, and will tI after operate the ringing` key .52- or the ringing; key according;` tothe plug Ieinployed.

f Then the called party respondshis telephone is introduced in bridge between the sides of his line whe eupon the relay 45, which is of high resistance, say 1,000 ohins, is shunted and "is therefore denergined whereby the relay L16 is placed within the control of* the called party or the control ofv the operator,which latter control is exercised by the withdrawal ol' *theplug troni the jack 3l. In this way the called party insures the breakage of the trunk conductor at when such called party restores "his receiver upon its switch hook, the private branch exchange operator not beine` relied upon to accomplish this result. The lowerinost arinature switch ofrelayet is vreleased so that the relay i8 is dener'gized to restore the norinal connection'of the battery 39 and the ground i9 'with the link cir.- cuit shown in Fig. G' to place the linesigf nal 5a of the private branch linev within the: control "of vthe called subscriber while his jacklis still engagedby the plug;- to enable the called subscriber to signal the operator by removing his telephone i'roin its switch hook, before the plug is removed from the jack. Thesigiial device 54 is also a clearing out-signal in that it is displayed during` they Aabsence of the receiver at thecalled station from the receiver switch hook and` is inert when the receiver is restored upon-'its switch hook. Y

The. batteryv 13 at' the niain l :echange shown in Fig. supplies battery current to 1f.

he connected stations, A the .K battery 39 at Athe private branch exchangeA then `taking no part in the supplyof b`attery""current to the branch exchange",station,l Ythough the branch vexchangeis, as far as local bran'clij exchange linesare concerned, acoininon 'battery systein. -i'tr i sy oi 'course understood that tl e manual,exchangefshown in rigs. tand 5 is a coniinon battery exchange.' v.

`rThel armature switchof the-relay 48 that l'ore ins. the connection' 'fof therbatteryBQ governs theconnection of arelay thatJ is norinall" inbridgejot the link circuit yscprated tronrthe coi'in'ec'ting'v end by a con-v denser5 6.`l Whenthe relay a8 is energized,

the relay is placed in shunt fof the con-.-

denser '56 so that the tip strand oi tlieass societe fco'rd; circuit is rendered in'etallieally continuous for the passage of straightA cur# l rent for the purposes which hare been de-l dition, if the operator l uponthe answering endet linko vcuit-,fthe answering endbeingscribed. In addition to the function et establishing a. inetallically continuous path about the condenser 5G, the relay .35, when energized, serves to establish circuit which inay be traced frein a grounded battery,

which inay be the battery 39, through a re# that circuit through this .relay G0 is closed at the contact when the operator Seel-:s to listen in.- The relay G0 is marginal so that it will not operate if current is furnished through the relay by way o' either resistance 59, 57 alone, but will operate i-these resistances are in parallel relation with each other and in serial relation with the relay. These resistances are individual to each of the operators keys at each operators posi- `tion and the uppermost Contact of each of such keys at each position is connected with the relay 60 at such position, whichA relay at each position is coniinon to such uppermost contacts of the operators keys at the saine position therewith. Such common connecl tions'.are illustrated withfthese uppermost contacts in each of Figs. 3 and 6. By ineans of this equipinentfan operator is prevented troni using` the equipinent of two cord circuits and the listening key ties pertaining ftlieieto tor the purpose of listening in upon an established connection. `Wlien the relayl GO is effectively energized its upper armature switch establishes a lshort circuit across the terminals of the operators telephone so that the operator cannotlisten in. The lower armature switch of. relay 60 when actuated will serve to establish a local circuit through a signaling device Gl to inform soine one in authority Athat the operator is not making proper use of her` facilities When the private branch exchange link circuit shown.

in Fig. 6 vis used for connecting two local lines, the relay 55, then exclusiif'ely associated with the answering` end of the link circuity and the relay 613L associated with the connecting'side of the link circuit, coperate to prevent the'operator from listening,r in upon an established connection, the relay partially placing the resistance 5T in' connection withthe listening switch contact 58 due to 'theabsence of the calling subscriber-s `tel`eplione-fi`r-oin its switch hook while the ielayl will complete the connection of the -resista-nce 57 with said contact 58 when the called subscribers' telephone is free of its switch hook.y with the result that the oper-- ator cannot listen in since the relay (30 will respond to .exclude the opcrators telephone 'troni circuit when 'the operator actuates her listening switch ior the purpose of includingh er set in circuit. In my application `Serial No. Gl3,339, led August 10,' 1911, I have incl udcd claims which cover the secrecy feature thus described.

In the description thus far `given, the station at the left hand end of Fig. l has been assumed to be the calling Vstation and the station at the right hand end of Fig. '6 has been assumed to lie the called station. `It the latter station is the calling station, then the connection is initiated. by the energization oit thesignal upon the removal of the receiver from its switch hook at the ,calling station.- The priv-ate branch operatorwill then insert a plug into'the ack 5 of the local line and will inscit the mate to said plug in the jack 31 that is free for use, whereupon the magnet 3l is energized in the manner which has been described to. establish breaks 32, in the trunk sides whereafter a signal is conveyed at the lamp G2 located at thcinain manual exchange due to a circuitv which ina-y be traced from a grounded battery, which may be the battery 13, through the relay 63, the upper armature yswitch of .the cutofl relay 6-1 to the trunk side 2land the metallic conductors that connect the same with the switch hook at the calling/station thence through the telephone outfit at the calling station to the trunk side 25, and the lower armature switch of the cutoff relay 6--1 to ground. The circuit that immediately causesthe signal lamp 62 to glow my be traced from the grounded battery 13 through the lamp to the armature switch ot' the relay G3. lVhen the operator at the main exchange responds by inserting the answering plugl 15 into the trunk jack 2S, a circuit is established through the cutotl relay (3l which may be traced from the grounded terminal of said cutolf relay through the thimble oit the ack 2S, the heel oi'l the answering plug` 15, the supervisory lamp 2O to the grounded battery 13, whereby the signal 62 is included in open circuit and the signal it has previously co1- .eyed is effaced. It will not be necessary further to describe the operations which occur when the call is initiated at aprivate branch station.

phone lilies, for accomplishing the results which are accoimplished by the equipment shown in F 4l, 5 and 6. In Fig. 1 and thelett hand portion of Fig. 2 I have illustra-ted.

a line extending from an automatic telephone exchange to a substation, at which substation means'are provided for eliecting the operation of the mechanism at the exchange automatically to effect the extension of the telephone line. At the substation shown in Fig. 1 I have illustrated a well known torni of circuit interrupter 65 to be operated by a subscriber initiating a call for the purpose of automatically connecting the calling subscribers line with a wanted extension thereof such as a trunk line that includes the talking sides 66, G7 and a local trunk line conductor 68 taking part in the control of the operation of the automatically operating line extending mechanism, all as is so well known to those skilled in the art as to require no further explanation. It has been assumed that the calling automatic subscriber desires communication with a private branch exchange line and thatthe calling subscriber has operated his circuit interrupting switch G5 for the purpose of connecting his line with the private branch exchange partially illustrated in Fig. 2. As a consequence of the automatic extension of the calling automatic subscribers line, the signal 35 is operated as a result of the i-nclusion of the calling generator (39 in bridge of the talking sides of the trunk line, all in a manner well understood by those skilled in the art. The operator at the private branch exchange in response to the signal conveyed by the automatic calling subscriber at the signal shown in Fig. 2 inserts the plug 8G of an idle link circuit in the jack 31 of the selected trunk line, whereafter operations are caused to ensue that are similar to the operations which have been described from this point on in the establishment of a connection between a calling main manual exchange line subscriber and a called private branch exchange line. I will therefore not describe the operations that occur from the automatic trunk signal 35 toward the called private branch lineas such a description would be similar to that given between similar p oints in the establishment of a connection `between the calling and called parties in the manual system shownA in Figs. l, 5 and G. It will therefore be considered that the former description of this portion of the operation will apply to the equipment shown in Figs. 1, 2 and 3, characters of reference used in Figs. 11, 5 and 6 being applied to parts that are similar to parts shown in Figs. 1, 2'and 3.

In the equipment shown in Figs. 1, 2 and 3, the private branch exchange lines1areadapted for connection with each other by link circuits having manually controlled ends 36 and 37, each linebeing provided with a signal 54 whereby the private branch operator may be made aware of the fact that one private branch line desires connection with another private branch line, a link circuit having the terminals 36,-37 that. were vhitherto described astorffiinga part of the connection between a calling main line subscriber and a called private branch exchange subscriber being of service in connecting two private branch exchange lines. The signal 54 also serves to inform the private branch exchange operator that a private branch line desires connection with a line extending to some other exchange, a line extending to branch line, and will insert the mate of said plug in the jack 31. Each private branch lstation may be equipped with a circuit interi-upter and each private branch trunk line section illustrated in Fig. 2 may be provided with a circuit interrupter 7l, whereby the calling private branch party, or the private branch operator, according to prcdeterinination, may automatically select and connect the calling private branch lineandv the selected trunk 6G, G7 with the linlr circuit similarly shown in Fig. l and tl'irough said link circuit with the called automatic line, all as is so well known by those skilled in the art as to require no further explanation.

In view of the apparatus which have employed toi' connecting an automatic calling subscriber with a private branch called line, some details of equipment are supplied to enable me to employ my equipment when a calling` private branch line is to become connected with a called automatic line,

with the aid ot the operators interrupter 7l, these additional characteristics not being necessary when the calling private branch party operates his calling switch 70. VV' hen the operator manipulates the circuit interiupter 7l for the purpose stated, she firstnianipulatcs her switch 72 for cutting the circuit intcnuptei 7l into circuit with the portions of the trunk line extending to the automatic exchange and thereafter separat-ing these portions ot the trunk line from the balance of the trunk line that belongs to the private branch exchange equipment, the switch 72 having normal followup contacts as illustrated. As a consequence of this operation of the switch 7 2, the relay 4G is denergized with the result that the relay 34 is released, under the assumption that the calling private branch party keeps his ltelephone O l its switch hook. To restore the relays 46 and 34 to their energized condition the key 72 is provided with extra 'contacts 73 that perform, in a way, the function ot' contacts 49. when the key 72 is operated, the' contacts 73 lestabllishing circuit through the relay 43 that indirectly causes the cnergization 'of the relay 34 ina manner which has been described in connection with Figs. 4, 5 and 6.

The automatic-exchange is a common baty tery exchange, the common battery connection being illustrated at 7 5 when .a private branchline calls an' automatic line. The connection of this common battery is illustrated at 76 when the automatic line is a calling line and the private branch exch ange line is a called line. The common battery at the automatic' exchange has its illustration repeated many times for the sake of simplicity, but it is understood that one battery may serve all the purposes where battery current is required. By means of my invention the automatic exchange conimon battery supplies current not onlyV to the automatic line but also to the private branch line, the private branch link connectors having the private branch exchange common battery removed from normal association therewith t0 permit the common battery at the automatic exchange to replace the common battery at the private branch exchange and perform whatever functions would otherwise be required ot the common battery at the private branch exchangewhen a private branch liuc is connected with an'automatic line either as a calling or called line. Thus my invention is of service in connection with an automatic exchange as well as with a manual exchange.

lt will be observed 'from what has been described and illustrated in connection with both systems shown in all ot the tigures that certain operating advantac are present when connection is e'iiected 'brtivcen a main line and a branch exchange line, it

niyselr" to exchanges that are strictly known as private bianchexchangcs when they are connected with lines extendiun` to main exchanges by the api'iaratus and in the ways which have been described. i have chosen an operator controlled branch exchange as an illustration, as my invention finds special adaptability in connection with exchanges of that type. Y'ihen a connection is effected between two exchange lines'and the telephone receiver at the connected private branch station is removed from hook, all bridges across the sides of the composite telephone circuit at the private branch exchange are broken, the relays 46 and 55 being the only relays that will rcspond when the private branch telephone receiver is restored .upon its switch hool-z.

these tworelays being serially related and in circuit with the main exchange battery, and performing the functions which have been described. it may be said that if the line signal 54. is also to perform the functhose' cases vvhere the-operator' fails. for some. reason or other -to take down' the connection line with-a called automatic line.

tion ot a clcruing out signal it', as an electromagnet, also serially included in the line. Bythus stripping the portion oi the composite branch exchange from continuous bridge connections i am enabled to avoid the faulty operation of the automatic equipment at the automatic exchange and the faulty operation of signals at the main manual exchange.

In the case of automatically established connections the private branch line may be provided with equipment that may rserve automatically to connect such private branch Willen a callingl party at the station of a line connected with the private branch exchange desires to become connected with a subscriber Whose line extends to the automatic exchange, such calling party Will remove his telephonefroin its switch hook and operate his line signal 54' to secure the attention of the private branch exchange operator who is informed by the calling party of the nunr ber of the desired automaticexchange subscriber, the private branch operator having connected a link circuit ivith the calling line in response to the signal conveyed at 54. The operator connects this link circuit Awith an idle trunk ack at 3l so as to connect the calling line with a line leading to the automatic exchange. The calling subscriber may automaticallyr extend his line at the auto matic exchange into connection with the desired automatic line by manipulatingthe switch at or the private branch exchange operator may do theV same thing by manipulating the switch at 7l ai'ter'the switch at 72 has been actuated to bring the switch 7l into circuit relation Wit-h the' line extending to the automatic exchange. The relay Si, when released upon the deenergization of the magnet i6 upon the restoration ot the Atelephone receiver of a connected private branch `sta-- tion, places the j ack section of the trunk line at the private branch exchange out of such association with the balance of this trunk line at .the privatebranch exchange that no device between the signal and the privatebranch lines can be operated through the main exchange unless the key 72 of F 2 is operated or the plug 3C of either Figs. 2 or 5`is withdrawn and reinserted in this j ack with the results that Vare vvell understood from the previous description. 1n this Way a main line subscriber, in again making connection with the trunk line, cannot, lasaj direct consequence, Secure connection with a` private 'branch line4 previously connected Wit-h that trunk line unless the key 7 or the plug 36' is manipulatedas` just described,

these provisions being-made to take -care of telephone circuit at the private lines extend; a second.commen'battery exsumption that at this-time no connection is to be established between such private branch station and the trunk line. l

Prior to this time of the response of a called branch line subscriber a bridge is maintained by the relay 44, the high resistance relay 45 being included in this bridge and serving to maintaina signal at Je? dur ing the maintenance of such bridge, the rclay 4:5 being shunted by the private branch subscriber when he removes his telephone from itsswitch hook whereby the signal i7. is rendered inert. The private branch exchange operator is thus enabled to determine when the private branch subscriber removes his telephone from its switch hook, the signal 4T constituting a holding signal individual to its associate trunk to enable the operator to determine Whether or not. the trunk has been taken by the private branch exchange subscriber. Then the connection has been concluded the loivermost armature switch of the relay 3i is restored to normal move the plug 37 from the vjack of the prif`i vate branch line before the private branch party attempts to make another call.

lVhile I have herein shown and vparticularly described the preferred embodiment of the invention, I donot Wish to be limited to the precise details of construct-ion and circuit. arrangement sho-Wn as changesmay readily bemade Without departing from the spirit of my invention. i

Having thus described my invention I irc claim as nevvand desire to secureby Letters Patent the .following l.l A telephone system including av common -batt-ery exchange to vwhich telephone change to Which'i other telephone lines ex.- tend'; a trunk line Aintel'vening between the exchanges to enable the establislimentof a connection Vbetween av telephone line extending t'o one exchange-and a telephone line extending'. to A-the 'second exchange,' tl'rere being linklconne'cters ati'the second exchange to 'the 'second' exchange. With ":the vtrui-1k.'line -t'or connecting 'lines extendingto the second exchangeand for, connecting lines Vendufi-g incase?.

inthe lestablishment of a connection between lines extending to the two exchanges; means I tend; a trunk line intervening between for removing the common battery of the second exchange from its normal relation with the link connector united vith thev trunk line at the second exchange to bring the common battery of the first exchange into operative association with said link connector at the second exchange; and subscriber controlled means for restoring the vcommon battery of the second' exchange to its normal relation vwith* the equipment thereat. Y

Qi. A telephone system including a coinnien battery exchange to which' telephone lines extend; a second common battery exchange to which other telephone lines extend; a trunk line intervening betweenthe exchanges to enablefthe establishment oic a connection between a telephone line extending to one excnange and a telephone line'extending to the second exchange, there being link connectors at the second exchange for connecting lines extending to the second vexchange and for connecting lines extending to the second exchange with the trunk line in the establishment of a connection between lines extending to the two exchanges; means for excluding the common battery of the second exchange from circuit' with the link connector nnitedvwith the trunk line at the vsecond exchange to bring the common battery of the iirst exchange' into operative association with said link connector' at the second exchange; and means controlled extraneonsly of the second exchange for restoring the common battery et the second exchange to itsk normal relation with the equipment there-at.

.3. it telephone system including a ceininon battery exchange to which telephone lines extend; a second common battery change to which other telephone lines A the exchanges to enable'the establishment ci? a connection between a telephone line extending to one exchange and a telephone line extending to the second z-ichange; there bei link connectors t the'second exchange connecting lines extending to the second c change and for connecting lines extending to the second exchange with' the trunk line in the establishment of a lconnection bctween'lines extending to the two exchanges: means for vremoving the common batteryv of the second exchange from its normal relation with the iink connector united with the.

ytrunk line at the second exchange to bring he common battery of the first exchange inte operative vassociat. ion with said iector at the second exchain i et broi Y it into circuit with the nien latterj, at the first exchange by r means to maintain this coi iaon nati in operative association with said link connector, said'inagnet serving when releasedfto effect therestoration of the normal relation"ofthev .common 'battery at the second` exchange y.with said link: connector. f l.

4; A-"telephone system including` a cointend; a trunk line intervening betweenthe exchanges't enable the establishment of a connection between a telephone line extending to oneexchange and a telephone line extending to the second exchange, there being link connectors at thesecond exchange for connecting lines extending to the second exchange and for connecting lines extending to the second exchange with the trunk line in the establishment of a .connection between lines extending to the two exchanges; means for excluding the common battery of the second exchange from circuit with the link connector unit-ed with the trunk line at the second exchange to bring the common battery ot the first exchange linto operative association with said link connector at the secondl exchange; and a magnet brought into circuit with the common battery at the irst exchange by the latter means to main-v mon battery at the second exchange with said link connector.

fr telephone system including a common battery exchange to which telephone lines extend; a second common battery exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a liectiini between a telephone line extend.- ing to one exchange and a telephone line extending to the second exchange; there being link canne tors at. the second exchange for connecting n.- es extending to the second exchange and tor connecting iines extending to the second exchange with the trunk line in the establishment oi a connecti n between lines extending to the two exchanges; means for removing the commen i attery et the second exchange from its normal relation with the link connector united with the trunk line tend; a trunk line intervening between the exchanges to enable' the establishment of a connection between a telephone line extending to one exchange and a telephone line extending to the second exchange, there being link connectors at the second exchange for connecting lines extending to the second exchange and for connecting lines extending to the second exchange with the trunk line in the establishment of a connection between lines extending to the two exchanges; means :tor excluding the common battery of the second exchange from circuit` with the link connector united with the trunk line at the second exchange vto bring the common battery of the first exchange into operative association with said link connecter at the second exchange; and

a magnet brought into serial relation with the common battery at the first exchange by the latter means to maintain this common battery in operative association with said link connector, said magnet serving when released to eiiect the resto-ration of the normal relation of the 'common battery at the second exchange with said link connector.

7. A telephone system including a common battery exchangeto which telephone lines extend; a second exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to the first exchange and a telephone line extending to the second exchange, there being a link connector .at the second exchange for connecting lines extending thereto with each other and 'with the trunk line; means for removing normal bridge connections at the second exchange troni the composite telephone circuit between stations of connected lines that extend to the exchanges; andv subscriber controlled means for restoring the normal bridge connections at thesecond exchange.

8. A telephone system including a cmmon battery exchange to which telephone lines extend; a second common battery exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to' one exchange and a telephone line extending to the second exchange, there being link connector at the second exchange for connecting lines extending thereto with each other and with the trunk line meansfor removing normal bridge connections at the second exchange from the composite telephone circuit between stations of connected lines that extend to the exchanges whereby the common battery at the first exchange may perform functions that would other-` wise be required of the common battery at the second exchange; and subscriber controlled means for restoring the normal bridge connections at the second exchange.

9. A telephone system vincluding a conimon battery exchange to which telephone lines extend; a second exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to the first exchange and a telephone line extending to the second exchange, there ,being a link connector at the second exchange for connecting lines extending thereto with each other and with the trunk line; means for excluding bridges at the second exchange from the composite telephone circuit between stations of connected lines that extend to the exchanges; and subscriber controlled means for restoring the normal bridge connections at the 'second exchange.

lO. A telephone system including a coinnion battery exchange to which telephone lines extend; a second common battery exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephonel line extending to one exchange and a telephone line extending to the second exchange, there being a link connector at the second exchange 'for connecting lines extending thereto with each other and with the trunk line; means for excluding bridges at the second exchange ing the normal bridge connections at the second exchange..

l1. A telephone system including a coniinon battery exchange to which telephone lines extend; a second exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment ofa connection between a telephone line extending to the first exchange and a telephone line extending to the second exchange, there being a link connector at the second exchange for connecting lines extending thereto with each other and with the trunk line; means for removing normal bridge connectionsat the second exchange from the composite telephone circuit between stations of connect-ed lines that 'extend to the exchanges; and a magnet associated with the composite telephone circuit' and in circuitwith the common battery at the first exchange to maintain the changes established in the bridge connections at the second exchange and serving when'denergized to permit the restoration of the 'nor- `mal relation of the bridge connections at the second exchange.

12. A telephone system including a common battery exchange to which telephone lines extend; a second common battery exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment otl a connection between a. telephone line extending to one exchange and a telephone iine extending to the second exchange, there being a link connector at the second exchange for connecting lines extending thereto with each other and with the trunk line; means for removing normal bridge connections at the second exchange :trom the composite telephone circuit between stations ot connected lines that extend to the exchanges whereby the common battery at the first exchange may perform functions that would Aotherwise be required of the common battery at the second exchange; and a magnet associated with the composite telephone circuit and in circuit with the common battery at the first exchange to maintain the changes established in the bridge connections at the second exchange and serving when denergized to permit the restoration of the normal relation ot the bridge connections at the second exchange.

13. A telephone system including a common battery exchange to which telephone lines extend; a second exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line .extending to the tirst exvrestoration of the normal relation of the bridge connections at the second exchange.

14. A telephone system including a com mon battery 'exchange to which telephone lines extend a second common battery exchange to which other telephone lines extend; atrunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to one exchange and a telephone line extending to the second exchange, there being a link connector atthe second exchange for connecting lines extending thereto with each other and with the trunk line; means for excluding bridges at the second exchange from the composite telephone circuit between stations ot connected lines that extend to the exchanges whereby the common battery at the first exchange may perform functions that would otherwise be required of the common battery at the second exchange; and a magnet associated with the composite telephone circuit and in circuit with the common battery at the first exchange to maintain the changes established in the bridge connections at the second exchange and serving when denergized to permit the restoration of the normal relation of the bridge connections at-the second exchange.

15. A telephone system including one exchange to which telephone lines extend; a second exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to one exchange and a telephone line extending to the second exchange, said trunk line having switching mechanism normally dividing it into separate sections; and a magnet governing said switching mechanism and located upon that side of the trunk line that is in more immediate association with the teleghone line of the Isecond exchange that is connected with said trunk line and within the control of the substation apparatus of this telephone line of the second exchange7 to join the trunk line sections when the latter telephone line is telephonically complete and to dis-l -second exchange to which other telephone lines extend; a trunk'line intervening between the exchanges to 'enable the establishment of a connection between a telephone line extending to one exchange and 'a telephone line extending to the second exchange, said trunk line having switching mechanism normally dividing it into separate sections; a magnet governing said switching mechanism and located upon that side of the trunk line that is in more immedia-te association with the telephone line of the second exchange that is connected with said trunk line and within the control of the substation apparatus or this telephone line of the second exchange tojoin the trunk line sections when the latter telephone line is teleph'onically complete and to disjoint the trunk line when the latter telephone line is telephonically incomplete; a. link connector for connecting the trunk line with said line of the second exchange; and means coperating with the link connector to permit the magnet to break the trunk line into sections.

into sections when the magnet is denernectorto enable the operation of said signal I at the second yexchangeto bring the comco tend tothe second exchange for restoring the a magnet governing said switching mechvice while theline to which said signal devlines extend; a second common batteryv exconnection between a telephone line extend- -ing to one exchange and a telephone line `for connecting lines extending to the second exchange and for connecting lines extending lines extending to the two exchanges; means for removing the commonbattery of the s econd exchange from its 'normal relation with .at theseccnd exchange; and means con- 17. A telephone system including one exchange to which telephone lines extend; a secondv exchange to which other ltelephone lines extend; a trunk line intervening between the exchanges to enable the establishnient of a connection between a telephone line extending to one exchange and a telephone line extending to the second exchange, said trunk line having switching mechanism normally dividing it into separate sections;

anism: a link connector for connecting the trunk line with a line extending to the second exchange; and means governed by the link connector for controlling the circuit of said magnet to divide the trunk line gized and to merge said sections when the magnet is energized.

1S. A telephone system including telephone lines. extending to one exchange; telephone lines extending to a second eX- change; a trunk line intervening between the exchanges; a link connector at the second exchange for connecting this trunk line with a line extending tothe second exchange; a signal device'individual to the line extending to the second exchange; an electro-magnet associated with 'the trunk line; a source of current for operating said signal device; and means `governed by said electro-magnet for yplacing said source ofA current in association with 'said signal device belongs is connected with the link condevice when the telephone at the 'assoc iate telephone station is removed from its switch hook. i

19. A telephone system including a coinmonbattery exchange to. which telephone change to which other telephone lines extend; a trunk line intervening between the exchanges to enable'the establishment of a extending to the second exchange, there being linkconnectors at`the second exchange to the second exchange with the trunk line in the establishment of a connection between the link connector united with the trunk line mon battery of the first exchange into opeiative'association with saidl link connector trolled by the subscribers whose lines ex.

common battery of the secondexchange to its normal relation with the equipment thereat.

20. A telephone system including a common battery exchange to which telephone lines extend; a second common battery ex'- .change to which other vtelephonek lines. ex-

in the establishment of a connection between lines extending to the two exchanges; means for excluding the common battery of the second exchange from circuit with the link connector united with the trunkline at the. second exchange to bring the common battery of the first exchange into operative association with said link connector at the` 'second exchange; and means controlled by the subscribers whose lines extend to the second exchange for restoring the common battery of the second exchange to its normal relation with the equipment thereat. A r

2l. A telephone system including one com-A i mon battery exchange to which telephone lines extend; af second common battery ex-4 change to which other telephone lines extend; a trunk line intervening between the exchanges to enable 'the establishment of a connection between a telephone line extending to one exchange and a telephone line extending to the lsecond exchange, said trunk linev having switching mechanism normally dividing 'it into separate sections; and a magnet governing said switching mechanism and located upon that'side of the trunk line that is in more immediate associationwith the telephone line of the second exchange that is connected with said trunk line and within the control of the substation apparatus of this telephone line of the second exchange to join the trunk line sections when the latter telephone line is telephonically complete and to disjoint the trunk linc when the latter telephone line is teleplionically incomplete.

22. A telephone system including `one comldividing. it linto separate. sections; a magnet 1 governingv said switching mechanism andlocated upon thatr side of the trunk line thaty is in more immediate association with the telephone linev of the second exchange that is connected with said trunk line and within the control of the substation apparatus of trunk line into sections.

2 3. A telephone system including one com- 'mon battery exchange to which telephone lines extend; a second common battery exchange 'to which other telephone` lines extend; a trunk line intervening between 'the exchanges to enable the establishment of a connection between a telephone line extending to one exchange and a telephone line extending to the second exchange, said trunk line -having switching mechanism normally dividing it into separate sections; a magnetA governing said switching mechanism; a link connector for connecting the trunk line with` `a line 'extending to the second exchange; and

means governed by the link connector for controlling the circuit of said magnet to divide the trunkline into sections when the magnet is denergized and to merge saidv sections when the magnet is energized.

24h A telephone system including telephone lines extending'to one common battery exchange; telephone lines extending to a second common battery exchange; a trunk line intervening between the exchanges; a link connector at the second exchange for connecting this trunkline with line extending to the second exchange; a signaldevice individual to the line extending to the second exchange; an electro-magnet associated with the trunk line; a source of current for operating said signal device; and means governed by said electro-magnet tor placing said source of current in association withsaid signal'device while the line to which said signal devicebelongs is connect- Vedwith the link connector to enable the operation of said signal device when the telephone at the associate telephone station is removed from its switch hook.

Q5. A telephone system including a common battery exchange to which telephone linesI extend; a second exchange to which other telephone. lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to the first exchange and a telephone line extending tothe second exchange, there being la link connector at the second exchange for connecting lines extending thereto with each other and with the trunk line; means for removing normal bridge connections at the second exchange from the composite telephone circuit between stations of connected lines that extend to the exchanges; and means controlled ext-raneously'of the second exchange for restoring"thenormal bridge connections at-the second exchange'. y 26. A telephone system including' a common battery exchange y to which '.-telephone-lines extend; la second common battery exchange to which other vtelephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to one exchange and a telephone line extending to the second exchange, there being a link connector at the second exchange -for connecting lines extending thereto witheach other and with the trunk line; means for removing normal bridge 'connections at the second exchange Vfrom the composite telephone circuit between stations of connected lines that extend to the exchanges whereby the common battery at the first exchange may perform functions that would otherwise ber required of -the common battery at the second exchange; and means controlled extraneously of the second exchange for restoring the normalbridge'connections at the second exchange.

27. A telephone system including a common battery exchange `to which telephone lines extend; a second exchange to which other telephone lines extend; a trunk line intervening between the exchanges to enable the establishment of a connection between a telephone line extending to the first exchange and a telephone line extending to the second exchange, there being a link connector at the second exchange for connecting lines extending vthereto with each other and with the trunk line; means for excluding bridges at the second exchange fromthe composite telephone circuit between stations of connected lines that extend to the exchanges; and. means controlled extraneously of the second exchange for restoring the normal bridge iconnections at the second exchange.

28. A telephone systemv including a common battery exchange to lwhich telephone lines extend; a second common battery` exchange to which other telephone lines extend; -a trunk linel uintervening between the exchanges to enable the establishment of a connection between a telephone line extending to Aone exchange ,and a telephone line extending lto the second exchange, there being 'a link connector at the second exchange for connecting linesA extending thereto with each .other and with.

the trunk line; means for excluding bridges at the second exchange. from the composite telephone circuit between stations of Aconnected lines that extend to the exchanges whereby the common battery at the first exchange may perform functions that would otherwise be required. of' the common batl tery at the second exchange; and I neanscon f trolledextraneouslyofthe second exchange.'

i mon"battery exchange .to which telephone lines extend; a second exchange'to which other telephone llines extend; a; ltrunk line intervening between the exchanges to enable the establishment of aconnection between a' telephone line v,extending to the. rst lex-A 'change-and a4 telephone line extending to the second exchange, there being alink connector at the second exchange for connecting linesl extendingv thereto with each othery and with the trunk line; means `for removing normalbridge. connections at the Second exchange from the composite telephone circuit between stations of .connectedI linesthat extend tothe exchanges; and means controlled by the subscribers whose lines extend to the"l -Second exchange g for restoring vthe normal bridge connections at the second exchangerA 30. A telephone system including a common battery exchange to which telephone lines extend; a secondv common batteryiexchangeto which other telephone lines extend; a trunk line intervening'between the. exchanges .to enable the establishment of a connection between a telephone line extend-- ing to one exchange. and a telephone line extending to the second exchange,'there'be ing a link connector at the second exchange for connecting lines extending thereto with each other and with the trunk'line'; means for removing normal bridge connections at' the secondl exchange Afrom the composite telephone circuit betweenstations of connected lines that extend to-the exchanges whereby theA common battery at the first exchange may perform functions that would otherwise be required of the common battery at the second exchange; and means controlled 'by the subscribers whose lines extend to the second exchange for restoring the normal bridge yconnections at the second exchange.A

.A 31. telephone system including a'c'omv mon battery exchange to which telephoneh50` lines. extend g a second exchange,V to which other telephone lines extend; a trunk-line(y intervening between-the exchanges to enabley l the establishment of a leonnectionbetween a telephone line 'extending to the first ex- 55 change and a telephone line extending to the second exchange, there being a link connectorl 'at the sccondexchange for *connect-V ing vlines extending theresewith` each other and with the trunk line; meansfor exclud- 6o ing bridges at the second exchange from the composite ,telephone circuit 'betweenY stations of connected lines that extend to the exchanges; and means controlled by'thesubscribers whose `lines'extend to the `second ex- 65 change for restoring-'thenormal bridge con` nections at the second exchange.'

32. A telephone system including a common battery exchange .to` which telephone l lines extend; a second common battery exchange towhich other telephonev lines' exvtend;fa trunk line intervening between the exchanges to enable the establishment of a. connection betweena telephone line extendf ingto one exchange and a ytelephone line e'x- 75 tending. tothe second exchange, there being a, link -connector at the secondv exchange` forl connecting lines extending. thereto with each otherand with the trunk line; means for exv `cludingbridges at the Secondfexchangefrom j the 'composite telephone circuit between stations of connected lines thatv extend to the exchanges whereby the common battery at thev first exchange may perforrn-functions that would otherwise be required ofthe eommon battery at the -second exchange; and `means controlled by the subscribers whose,

lines extend Ato the .second exchange forrestoring lthe normal bridge connections at the second exchange. v v

f In witness whereof, I hereuntoz subscribe my name this 24th 'day of July A. D., 1911.

MORTON lL.y JOHNSON. Witnesses: j

E. L. wenn G. L; CRAGG." 

